Commercially available 3D printers, such as the ProJet™ 3D Printers manufactured by 3D Systems of Rock Hill, S.C., use build materials (also referred to as inks in some instances) that are jetted through a print head as a liquid to form various 3D articles or parts. Other 3D printing systems also use a build material that is jetted through a print head. In some instances, the build material is solid at ambient temperatures and converts to liquid at elevated jetting temperatures. In other instances, the build material is liquid at ambient temperatures. Still other 3D printers form 3D articles or objects from a reservoir, vat, or container of a fluid build material or powdered build material. In some cases, a binder material or a laser or other source of energy is used to selectively solidify or consolidate layers of the build material in a stepwise fashion to provide the 3D article.
Build materials for 3D printing systems can include one or more colorants or pigments to provide colored printed parts. However, many such build materials are much more highly pigmented than necessary or desired to provide colored printed parts. Moreover, the presence of pigments in many build materials can interfere with the jettability, stability, and/or curability of the inks. In addition, the pigment load of some pigmented build materials can require different types and/or amounts of photoinitiators to obtain appropriate curing of build materials having different colors, which can result in decreased efficiency and/or increased cost of a 3D printing process.
Moreover, prior methods of printing color 3D articles fail to provide 3D articles having variation in color with depth from the surface of the articles, thus limiting the colorization of 3D printed parts.
Therefore, there exists a need for improved methods of color 3D printing and improved build materials for color 3D printing.